An intensive aerosol and water vapour measurement campaign, started on June 2002, is in progress at IMAA in Tito Scalo (PZ) (Southern Italy, 40°36'N, 15°44'E, 820 m above sea level) in the frame of the validation program of ENVISAT. Systematic measurements, using both active and passive ground based instruments, will be performed for a period of 12 months, in coincidence with ENVISAT overpasses. A Raman lidar system is used to perform both aerosol and water vapour measurements; aerosol backscatter and extinction coefficients are retrieved from simultaneous elastic signals at 355 nm and inelastic N2 Raman backscatter lidar signals at 386.6 nm, whereas, water vapour mixing ratio measurements are retrieved from simultaneous H2O and N2 Raman signals. A sun-photometer based on a Mechelle spectrometer is used to measure direct solar irradiance in the wavelength range 300 ÷ 1100 nm and a Fourier infrared spectrometer is used to measure vertical sky radiance in the range 500 ÷ 3000 cm-1. All the observations are complemented with radio-sonde launches. Two measurements per week are scheduled for the first six months of the validation campaign, while one measurement per week is scheduled for the last six months. First results of the measurement campaign are presented.